and 5.5 x 10 -8 mm -3 /N m, respectively. Through Raman spectroscopy and electron microscopy it was confirmed the carbon-carbon contact, due to the tribolayer formation on the wear scars of the coating and pin. In order to further corroborate the experimental observations regarding the graphitisation behaviour, the existing mathematical relationships to determine the graphitisation temperature of the coating/steel contact as well as the flash temperature were used.

evaluation of hydrogenated and silicon DLC coatings on carbon steel for use in valves, pistons and pumps in oil and gas industry, Wear,

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The microstructure of CrN/AlN films, prepared by reactive magnetron sputtering under various conditions, was analyzed and related to the wear behavior of the films. One set of films was prepared by conventional reactive magnetron sputtering, a second set adding an extra amount of reactive gas to the initial Ar + N 2 mixture and a third set adding an extra source of nitrogen near the substrate during sputtering. The samples were analyzed by scanning electron microscopy + energy dispersive microanalysis, high resolution scanning electron microscopy, atomic force microscopy, and x-ray diffraction. The results of the microstructural analysis revealed a clear difference in the morphology growth of the films when extra nitrogen was used compared to the conventionally prepared films. Formation of CrN was significantly faster than that of AlN. The most effective method to produce AlN was to introduce extra nitrogen. Pin-on-disk wear experiments were carried out in ambient air, to investigate the tribological behavior of the CrN/AlN system against a steel ball under dry conditions for various loads and a constant sliding speed. The results revealed that tribological properties of the layers improved unlike those of the untreated H13 steel. The friction behavior is closely related to the structure of the deposited films. The thicker CrN layer contributed to the higher load capacity of the coated steel when compared to the unmodified steel. However, wear life for the coating system was very short, denoted by the fairly poor adhesion of the film system to the steel substrate.

Decellularised porcine superflexor tendon (pSFT) has been demonstrated to be a suitable scaffold for anterior cruciate ligament reconstruction[1]. While the role of collagen in tendons is well known, the mechanical role of glycosaminoglycans (GAGs) is less clear and may be altered by the decellularisation process.To determine the effects of decellularisation on pSFT GAG content and mechanical function and to investigate the consequences of GAG loss in tensile and compressive loading.pSFTs were decellularised following previous techniques [2]. For GAG removal, native pSFTs were treated with chondroitinase ABC (ChABC; 0.1U/mL, 72h). Cell and GAG removal was validated using histology and quantitative assays. Native, decellularised and ChABC treated groups (n=6) were biomechanically characterised. In tension, specimens underwent stress relaxation and strength testing using previous protocols [1]. Stress relaxation data was fitted to a modified Maxwell-Weichert model to determine time-dependent (E1 & E2) and time-independent moduli (E0). The toe and linear region moduli (Etoe, Elinear), in addition to tensile strength (UTS) and failure strain were determined from strength testing. In compression, specimens underwent confined loading conditions (ramp at 10 s-1 to 10% strain and hold). The aggregate modulus (HA) and zero-strain permeability (k0) were determined using previous techniques [3]. Data was analysed by one-way ANOVA with Tukey post-hoc test to determine significant differences between test groups (p<0.05).Quantitative assays showed no GAG reduction post-decellularisation, but a significant reduction after ChABC treatment. HA was only significantly reduced in the ChABC group. k0 was significantly higher for the ChABC group compared to decellularised. E0 was significantly reduced in the decellularised group compared to native and ChABC groups, while E1 and E2 were not different between groups. Etoe, Elinear, UTS and failure strain were not different between groups.Decellularisation does not affect GAG content or impair mechanical function in pSFT. GAG loss adversely affects pSFT compressive properties, revealing major mechanical contribution under compression, but no significant role under tension.

The effect of holding time on the microstructure and corrosion resistance of the junction zone of AISI 316L bonded to AISI 304 stainless steels (SSs) at 960uC using an Fe based alloy filler was investigated. Samples of austenitic SSs were joined in a sandwich-like arrangement using noncommercial Fe 60 Ni 12 Cr 8 P 13 B 7 metallic glass ribbon. Microstructural analysis revealed significant dissolution of the amorphous ribbon in both SSs for short holding times, exhibiting a narrow interlayer with very fine precipitates. Larger holding times induced widening of the interlayer and coarsening of c precipitates in the iron based alloy and significant variation of the interlayer chemical composition. Microstructural dissimilarity of the bonding zone promoted selective dissolution coupled with crevice corrosion of the joints in 3?5 wt-% sodium chloride solution. In general, at the joining temperature of 960uC, the bonding ribbon and the AISI 316L SS presented higher corrosion resistance as the holding time increased up to 20 min.